Phosphomolybdic acid supported on Schiff base functionalized graphene oxide nanosheets: Preparation, characterization, and first catalytic application in the multi‐component synthesis of tetrahydrobenzo[a]xanthene‐11‐ones

Abstract

New Schiff base (SB) functionalized graphene oxide (GO) nanosheets containing phosphomolybdic counter‐anion H2PMo12O40¯ (H2PMo) were successfully prepared by grafting of 3‐aminopropyltriethoxysilane (APTS) on GO nanosheets followed by condensation with benzil and finally reaction with phosphomolybdic acid (H3PMo12O40, denoted as H3PMo) and characterized using Fourier transform infrared (FT‐IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), particle size distribution, energy‐dispersive X‐ray (EDX) analysis, EDX elemental mapping, and inductively coupled plasma optical emission spectrometry (ICP‐OES). The prepared new nanomaterial, denoted as GO‐SB‐H2PMo, was shown to be an efficient heterogeneous catalyst in one‐pot, three‐component reaction of β‐naphthol, aldehydes, and dimedone, giving high yields of tetrahydrobenzo[a]xanthene‐11‐ones within short reaction times. The catalyst is readily recovered by simple filtration and can be recycled and reused several times with no significant loss of catalytic activity.

Preparation, Characterization and First Application of Graphene Oxide‐Metformin‐Nickel for the Suzuki Cross‐Coupling Reaction

“…As shown, the catalyst has a size between 30 nano meter to 10 micro meter which probably the small parts are related to the organic (metformin) and inorganic ligands (nickel nanoparticles) attached to the GO nanosheets and the big parts are attributed to the GO nanosheets surface. These results are in agreement with TEM and SEM analyses …”

“…These results are in agreement with TEM and SEM analyses. [23] Scheme 1. Synthesis of Ni(0) coordinated to metformin-graphene-oxide (GO-Met-Ni(0)) Scheme 2.…”

Photophysical and Electrochemical Studies of Anchored Chromium (III) Complex on Reduced Graphene Oxide via Diazonium Chemistry

“…The other distinct peaks are 1710 cm −1 (C=O), 1149 cm −1 (C-OH) and 1031 cm −1 (C-O) represent the hydroxyl, carboxylic and epoxy groups. [55][56][57][58][59][60] The FTIR spectrum respectively. [32] The peaks at 1106 cm −1 and 1019 cm −1 correspond to the Si-O-Si and Si-O-C, confirms the silane coupling of rGO.…”

Catalytic evaluation of newly prepared GO-SB-H2PMo as an efficient and reusable nanocatalyst for the neat synthesis of amidoalkyl naphthols

“…Considering the unique properties of functionalized GO nanosheets, very recently, a novel Schiff base (SB) functionalized GO containing phosphomolybdic counter-anion H2PMo12O40¯ (H2PMo), denoted as GO-SB-H2PMo, was successfully prepared by grafting of 3aminopropyltriethoxysilane (APTS) on GO nanosheets followed by condensation with benzil and finally reaction with phosphomolybdic acid (H3PMo12O40, denoted as H3PMo) and fully characterized in our group (Scheme 1). This new reusable catalyst performed well and showed a high level of catalytic activity in the synthesis of tetrahydrobenzo [a] xanthene-11-ones [48]. Prompted by these facts and as part of our research on the development of environmentally friendly methods for the synthesis of organic compounds using reusable catalysts [49][50][51][52][53][54][55][56][57][58][59], we report here another application of GO-SB-H2PMo as catalyst in the synthesis of amidoalkyl naphthols 4a-k via the reaction of βnaphthol 1 with aryl aldehydes 2a-k and acetamide 3 under neat conditions (Scheme 2).…”

“…This is followed by addition of benzil (1.5 mmol, 0.32 g) and a few drops of glacial acetic acid. The mixture was heated under reflux for 5 h. The solid was filtered and washed with absolute ethanol (3 × 5 mL) to remove the non-reacted benzil, and then dried at 40 °C under vacuum for 24 h to give GO-SB [48].…”